<form class="form-inline">
  <div class="input-group">
    <input type="text" class="form-control" ng-model="main.filter.$" placeholder="Global Search...">
    <span class="input-group-btn">
      <button type="button" class="btn btn-info">
        <span class="glyphicon glyphicon-search" aria-hidden="true"></span>
      </button>
    </span>
  </div>
</form>